Multipath Digital Microphone With Adjustable ADCs
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Solution Overview
Problem
Conventional digital microphones face challenges in achieving high dynamic range with low power consumption and flexible performance adjustments, often resulting in audible artifacts and inefficient power management, particularly in mobile devices exposed to varying sound pressure levels.
Innovation Solution
The implementation of a multipath digital microphone system with adjustable ADCs, a gain adjustment component, and a power management component that allows seamless transitions between signal paths and power states, enabling flexible performance modes without interruptions in audio output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional digital microphone techniques (high DR ADC or AGC) are employed to improve dynamic range, then dynamic range is improved, but power consumption becomes excessively large
Solution Approach 1:
The patent divides the audio signal processing into multiple parallel signal paths, each optimized for specific dynamic range segments. The system segments the ADC operation into different modes (first mode with higher power for extended dynamic range, second mode with lower power for reduced dynamic range) and selectively activates paths based on signal levels, resolving the contradiction between achieving high dynamic range and maintaining low power consumption.
Solution Approach 2:
The patent implements dynamic switching between different operational modes and signal paths based on real-time signal level detection. The system dynamically adjusts which ADC paths are active and modifies operating parameters (such as oversampling ratio) according to the current audio signal characteristics, enabling the microphone to adapt power consumption to actual performance requirements rather than operating at fixed high power levels.
2Measurement precision
If conventional digital microphone techniques (AGC or high DR ADC) are employed to improve dynamic range, then dynamic range is improved, but troublesome artifacts are introduced
Solution Approach 1:
The patent segments the dynamic range handling into different signal paths, with each path optimized for specific signal level ranges. By dividing the processing into multiple specialized paths rather than using a single AGC chain, the system avoids the artifacts generated by aggressive gain adjustment while still achieving extended dynamic range coverage across all signal levels.
Solution Approach 2:
The patent introduces digital signal processing intermediaries (such as digital gain adjustment and selective path combining) between the analog front end and final output. These digital intermediaries replace analog AGC mechanisms that generate artifacts, providing dynamic range extension through clean digital operations that can be precisely controlled and artifact-free.
3Use of energy by moving object
If specific analog front ends are used to reduce power consumption, then power consumption is reduced, but signal to noise ratio performance deteriorates
Solution Approach 1:
The patent replaces analog front-end power reduction techniques with digital signal processing approaches. Instead of using low-power analog circuits that inherently have poor noise performance, the system uses digital gain adjustment, digital filtering, and digital path selection after high-quality analog-to-digital conversion, achieving power efficiency through digital operations that preserve signal-to-noise ratio.
4Measurement precision
If multipath approaches are used to extend dynamic range, then dynamic range is improved, but instantaneous saturation effects occur due to combining algorithm
Solution Approach 1:
The patent applies preliminary digital gain adjustment to each signal path before combining them, ensuring that no path contributes saturated or clipped signals to the final output. By pre-normalizing the signal levels in each path based on detected signal characteristics, the system prevents instantaneous saturation effects that would otherwise occur during the combining algorithm when high-level signals from one path interact with the combination process.
Data Source
AI summary
Disclosed embodiments provide flexible performance, high dynamic range, microelectromechanical (MEMS) multipath digital microphones, which allow seamless, low latency transitions between audio signal paths without audible artifacts over interruptions in the audio output signal. Disclosed embodiments facilitate performance and power saving mode transitions maintaining high dynamic range capability.